Electrolyzers for the production of magnesium

ABSTRACT

An electrolyzer for the production of magnesium comprising a refractory material-lined bath with a bottom (hearth), a cover and electrodes inserted into the bath and connected to busbars, wherein on the bottom of the electrolyzer bath provision is made for a coating connected to the cathode busbar.

[ 5] Oct. 23, 1973 [51] Int. Cl. C22d 3/02, C22d 3/08 [58] Field of Search................... 204/70, 243 R-247 [56] References Cited UNITED STATES PATENTS OF MAGNESIUM [76] Inventors: Konstantin Dmitrievich Muzhavlev,

Zheleznovodskaya ulitsa, 38, kv. 30; Sergei Petrovich Kosarev, Nalichnaya ulitsa, 39, korpus I kv.

United States atent Muzhavlev et al.

[ 1 ELECTROLYZERS FOR THE PRODUCTION ABSTRACT An electrolyzer for the production of magnesium com- Day Day.........

Wood Johnson 3 Claims, 2 Drawing Figures (hearth), a cover and electrodes inserted into the bath and connected to busbars, wherein on the bottom of Primary Examiner-John H. Mack Assistant Examiner'D. R. Valentine Attorney-Eric H. Waters et al.

prising a refractory material-lined bath with a bottom the electrolyzer bath provision is made for a coating connected to the cathode busbar.

20; Grigory Petrovich Khristjuk, 2O Linia, 7, kv. 23, all of Leningrad; Jury Nikolaevich Boiko, ulitsa Rekordnaya, 43, kv. l3, Zaporozhie; Oleg Andreevich Lebedev, Novoiz mailovsky prospekt, 26, korpus 2, Leningrad; Vladimir Dmitrievich Yazev, Bogdana Khmelnitskogo, 66, kv. 59, Kalush lvano-Frankovskoi Oblasti, all of U.S.S.R.

[22] Filed: Aug. 26, 1971 [21] Appl. No.: 175,090

ELECTROLYZERS FOR THE PRODUCTION OF MAGNESIUM This invention relates to electrolyzers for the production of magnesium.

An electrolyzer for producing magnesium is known in the art, which comprises a refractory material-lined bath with a floor (hearth), a cover, graphite anodes and steel cathodes, which electrodes are inserted into the bath. Anode contact conductors are disposed on the bath floor, while cathode contact conductors are provided in the side walls of the bath. Graphite bars are placed on the bath floor in abutting relationship to one another.

However, said prior art electrolyzer has a short service life and is an expensive apparatus. Connecting the contact conductors to graphite bars involves major difficulties. Indeed, despite accurately mating contact surfaces, electric resistance in the sites of contact is excessively high, whereby power consumption is increased and the process of electrolysis is rendered prohibitively expensive. 7

It will also be noted that the contact conductors connected to graphite bars in the bath floor have a short useful life due to the electrochemical deterioration of contact surfaces and a continuously increasing resistance offered by the contacts.

In the course of electrochemical deterioration of the contact conductors, there occurs electrolyte contamination with the products of contact conductor deterioration, so that current efficiency diminution and higher power consumption are the phenomena arising during electrolyzer operation.

Cathode contact conductors disposed in side walls of the bath likewise fail to provide for prolonged electrolyzer operation inasmuch as the refractory lining of the bath at the sites of contact conductor entry undergoes electrochemical deterioration which result in a further decrease in the current efficiency and also in greater power losses.

The employment of cathode contact conductors in the form of steel beams disposed in the bath bottom and rigidly connected to conductor rods passing through the bath bottom (cf. The USSR inventors certificate No. 246073) was beneficial as long as this arrangement made it possible to diminish the resistance offered by contact and to prolong their service life, but failed to eliminate all the aforementioned drawbacks of the prior art electrolyzer, since in the intervals between cathode beams there occurred the electrochemical dissolution of the bottom lining material.

It is an object of the present invention to provide an electrolyzer for the production of magnesium noted for its longer service life as a result of employing an appropriate conducting coating on the bath bottom.

It is another object of the present invention to provide an electrolyzer for the production of magnesium noted for its improved efficiency.

These and other objects are accomplished by the provision of an electrolyzer for the production of magnesium comprising a refractory material-lined bath with a bottom (hearth), a cover, and electrodes inserted into the bath and connected to busbars wherein, according to the invention, the bath bottom is furnished with a conducting coating connected to a cathode busbar.

The electrolyzer, in accordance with the invention, is noted for its longer service life and improved efficiency.

The conducting coating on the bath bottom is preferably made of at least one steel plate that contacts at least one cathode, the contact conductors to said plate passing through the bath bottom.

The advantages arising from the use of steel plates to obtain a conducting coating are associated with design simplicity and ease of erection and dismentling. It will be noted that mounting the steel plates so as to provide a clearance therebetween eliminates steel plate deformation under the effect of elevated temperatures.

The present invention will be fully understood by reference to the ensuing description of an exemplary embodiment of the electrolyzer for the production of magnesium, and accompanying drawings, in which:

FIG. 1 is a vertical section taken across the electrolyzer, according to the invention; and

FIG. 2 is a vertical section taken along the electrolyzer, according to the invention.

The present electrolyzer for the production of magnesium comprises a refractory material-lined bath 1 (FIGS. 1 and 2) enclosed in a steel shell 2. The bath 1 is furnished with a bottom (hearth) 2 and a cover (roof) 4, which supports anodes 5 inserted into the bath 4. Cathodes 6 are mounted on the bottom 3 and protrude into the bath 1. Provision is made in the bath bottom 3 for a coating made of steel plates 7, which are rigidly coupled to current distributing beams 8 furnished with conductor rods 9 that are connected to cathode busbars 10. The anodes 5 are connected to anode busbars 11.

In the present embodiment, the bottom coating 7 is comprised of a plurality of steel plates which contact at least one cathode 6 and are furnished with contact conductors 9 passed through the bottom 3 of the bath 1. In another-embodiment of the invention, the bottom coating 7 may consist of a solid plate also made of an electroconducting material. The bottom coating 7 is intended to afford protection to the lining of the bath bottom 3 from electrochemical dissolution and, hence, to eliminate electrolyte contamination.

To draw off the evolved chlorine, the electrolyzer is furnished with at least one connection 12.

In the electrolyzer, provision is made for at least one magnesium collecting kettle 13 separated from the cell units by a partition 14.

The electrolyzer, according to the present invention, functions as follows.

The pre-dried bath 1 (FIGS. 1 and 2) is charged with the magnesium chloride-containing electrolyte to a level adequate for immersing the cathodes 6 completely.

Direct current is supplied to the anodes 5 and cathodes 6 via the busbars l1 and 10. During the process of electrolysis, chlorine is evolved at the anodes 5, while magnesium is discharged at the cathodes 6.

From the bath 1, the chlorine is withdrawn by a pump (not shown in the drawings) via the connection 12, whereas the magnesium collected in the kettle 13 is removed by conventional means.

The results of electrolyzer testing are indicative of an at least two-fold increase of the electrolyzer service life, while the current efficiency is increased by l 2 percent and the power requirements are diminished by l 2 kW-hr per kg magnesium.

2. The electrolyzer as defined in claim 1 including contact conductors to said plates and passing through said bottom of said tank.

3. The electrolyzer as defined in claim 2 wherein said plates are spaced from each other for leaving a clearance between said plates to reduce substantially deformation of said steel plates at elevated temperatures. 

2. The electrolyzer as defined in claim 1 including contact conductors to said plates and passing through said bottom of said tank.
 3. The electrolyzer as defined in claim 2 wherein said plates are spaced from each other for leaving a clearance between said plates to reduce substantially deformation of said steel plates at elevated temperatures. 